Construction of floating vessels



1,622,830 Mimh 29 1927- J.`w. lsHERWooD CONSTRUCTION OF FLOATING VESSELS Filed June l2. 1924 3 Sheets-Sheet 1 l 622 830 March 29 1927" J. w. lsHERwooD CONSTRUCTION oF FLOA'TING vEssBLs Filed June 12. 1924 l s sheets-sheet 2 im am Patented Mar. 2,9, 1927.

JOSEPH W. ISHERWOD, 0F CHISLEHURST, ENGL-AND.

`coNs'rJaUc'rIoN oir Applicationn'led :une 12, 1924, smal no.'

'lhis invention r'elatesto floating vessels especiallyv adapted, but not exclusively, to the carrlage of vpetroleum or other liquids in bulk and which are built in accordance with what is universally known as the Isherwood system of ship constructlon, an example of which isillustrated in U. S. Patenti #1,029,546, dated June 11, 1923.

Said vessels as is well known, are rovided 1o withV bulkheadsto form the tanks 1n which the petroleum is stored, und the skin ofthe ship and these bulkheads are usually stiffened by longitudinal. and horizontal members which have been, rior to this invention,

i bracketed to the plating and to each other the same time, not require an excessive weight of metal. y

- Referring to the accompanying drawings i forming a part of this'specification, in which like numerals designate like parts in all the 3 views:

Figure 1 isa diagrammatic plan view ofl an oil carrying tank stitfened in accordance with this invention;

Figure 2 is a view of a somewhat modified form of structure (stiii'ening at the corners of the tank) Fi ure 3 is a view of a still further modiied orm of structure stifening that may be usedlat the corners of the tank;

Figure 4 is a sectional view taken on the line 4-4 of Figure 2;

Figure 5 is a sectional View on the line 545 of Figure 3;

Figure 6 is a view similar to Figure 1, but showing a modified construction of stifening employing brackets on the webs of the sides of the tanks; h

Figure 7 lillustrates a still further modified Lmeans of stiiening the tanks;

50. Figure 8 shows a common form of stitening the tank with the brackets heretofore employed;

" Figure 9 is a diagrammatic perspective view of a ortion of the sides of an Isherwood vesse fitted with a bulkhead forming a part of a tank; A

rI-.oATING vEssELs. y

719,575, and in creat mmm my 17, 1923.

Figure 10 is a stillfurther modified form of stiiiening for the' corners of vtanksmade in accordance with this invention; and

Figure 11 is a sectional view on the'line 11-#11 of Figure 10.

In order that the precise invention may be 4the more clearly understood, reference will frstbe had more particularly to Figures 8 and 9, and it is said:

As is well known, the general practice in the construction of these oil carrying vessels, or so called tankers, when built on what is now known aslhe lsherwood system, is to provide supports for the skin 1 and deck'2 ot' the vessel by fitting at widely spaced longltud'nal intervals'strong transverse frames 3 and beams 4, which are spaced from veight to twelve feet apart, there being no intermediate transverse frames or beams between the said strong transverse frames and beams hereinafter called transverses. Each of the transverse bulkheads 5 forming a wall of an oil compartment 6, and'which are fitted in these tankers at longitudinal intervals of from, say, twenty to thirty feet apart, takes the place of a transverse. It is further well known that in association with these transverses 3 and bulkheads 5 there are fitted in said tankers a series of longitudinal frames 7 and longitudinal beams 8 spaced from, say,

twenty-four to thirty-six lnches apart to com lete the supports of the skin and deck of t e ship. These longitudinal frames 7 and beams 8 hereinafter are called longitudinals.

The plating of the transverse bulkheads 5 in these tankers is further stiiiened by fitting vertical webs 10 at transverse intervals of from, say, six to ten feet apart, and in association with these last named members 10 there are provided aseries of hori- `zontal stiffeners 12 running transverselyof the vessel, the spacing of' which corresponds approximately to the longitudinals 7 of the skin of the ship.

As is further well known, the strength or dimensions of the transverses 3 at the sides `and at the bottom of the ship respectively are largely determined by the load they have to sustain, and the strength or dimensions otn the webs 10 on the transverse bulkheads are determinedon the same basis.

For the purpose ot' comparison ot' strengths and in some measure in arriving at the dimensions of the longitudinals ot' the bottom sides and deck of the ship the trans-` verse bulkhead 5 and the'tra'nsverses 3 are regarded as fixed points, and in like manner the webs 1() on the transverse bulkhead are also regarded as fixed points in arriving at the size of the horizontal stifeners 12 carriedby said transverse bulkhead. In nearly all of such tank vessels, it is the well known practice to fit the bulkhead -15 at the middle line of the ship running longitudinally for the length of the oil carrying spaces. This middle line bulkhead 15 is stiffened in like manner as the sides of the ship by the transverse bulkheads 5 and the vertical webs 16 and a series of longitudinal stifi'eners 17. The webs 10 and 16 on the transverse and middle line bulkheads can either be fitted on theisame sides as the longitudinals and horizontals as is illustrated in Figure 8, or

' they can be fitted on the opposite side of the bulkheads 5 and 15, as may be desired. Likewise, in cases where for any particular purpose it is desired to place the longitudinals 7 of the skin of the shipon the outside of the plating 1, such for instance as for tendering purposes, such disposition of said longitudinals of course can be had.

Each of the longitudinals 7 at the side of the ship -and the longitudinal stitleners 17 on the middle line bulkhead 15 and likewise each of the horizontal stifeners 12 on the transverse bulkheads are assumed to be girders having a span corresponding to the distance between their corresponding trans- ,verses or webs and having fixed supports at the points of intersection of transverses and webs.

It is further well known that at the points of junction of the transverse bulkheads 5 withpthe skin 1 and deck 2 of the ship the longitudinals 7 of the skin and the longitudinals 8 of the deck are each discontinued. Further, the` horizontal stiieners 12 ofy the transverse bulkheads 5 are likewise each discontinuous where they meet the skin of the ship, but it is the ycommon practice to fit each of these members 7, 17, and 12 with brackets 18 to connect the parts so-that the may be regarded as .having fixed ends, al as will be clear from Figure 8. When these brackets are employed the distances between the transverses or webs are equal to or less than the distances between the transverses or webs and the corners of the tank compartment. l l

The longitudinal stifi'cncrs 17 on the middle line bulkhead 15 are dealt with in the same manner. That is, they are connected by brackets 19 at the corners of the tank with the transverse stiffeners 12. But experience has shown that these said brackets 18 and 19 which might be described as corner brackets are not only expensive to .tit but constitute stitfened areas that are conducive to leakage at their points of riveting whenl a vessel is stressed in heavy seas or when the parts are subjected to heavy loads as intimated above.

Therefore. the object of this invention, as above stated is to eliminate these cOrner brackets 18 and 19 or many'. of them, without sacrificing the strength of the bracing structure and without requiring a prohibitive weight of metal. To accompllsh this, I proceed as follows: The longitudinale 7 and 8 of the skin and deck plating and the horizcntals 12 and 17 of the transverse and middle line bulkheads are stopped short of the corners of the tanks as is usually done in the present practice of building according to the Isherwood system. But according to thisl invention, these stiffening members are not provided with any corner brackets 18 and 19 at all. Instead of said brackets, as will be clear from Figure 1, I support the longitudinals 7 of the skin 1, and the longitudinals 8 ot the deck, Figure 9, as well as the horizont-als`17 of the middle line bulkhead 15, preferably by two or more transverses or webs 16 in each oil tank, and tit preferably two or more vertically disposed webs 10 on the transverse bulkheads between the middle line bulkhead 15 and the sides 1 of the ship.

I so dispose these transverses or webs 10 and 16 that the distances 25 between the said webs or transverses are greater than the lengths 26 of the projecting end spans of the longitudinals 7 and 17 and of the horizontal members 12. In other words, the lengths of` the ends 26 of the longitudinals or horizontals, instead of being equal to or greater than thelengths 25, are always less than said lengths 25, and in making the calculations.' of strengths, they are treated as beams whose portions 26 are fixed at said transverses or webs and are not to be connected bybrackets. Said ends 26 `being unconnected by brackets, may now be calculated and made of such dimensions or cross sections as will cause their strength to be substantially the same hs the stren h of the portions 25 of the same stifl'ener ocated between the points supported or assumed tot fixed by the transverses or Webs.

No arbitrary length of projecting ends 26 of the longitudina or horizontal stiieners, however, can be fixed in relation to the distance 25 between the points of support given by the transverse webs 10 or 16, for this ratio may vary from 40% to 80% or thcre- 120 abouts, depending on the arrangement adopted whether the end of the )rejecting portions is regarded in the calcu ations as ree or simply supported.

It will, however, be obvious that by in 125 creasing the distance 25 between a pair of transverses 16 or-webs 10, so as to lessen the lengths of the projecting ortions 26, said longitudinale or horizonta s must be substantially increased in size or weight as 13 lill com ared with thosel in association with 'length espias .'aianer Las@ leiie equa 1y spaced transverses or webs buththese or transxrersesl can -be increased beyondfthe 'increases will be equalled by the saving of lower limit of 40%,above1stat'ed- I Tlieun# weight due to the elimination of corner brackets. V

It should also be understood that the len ths 26 of thev projecting portions of the sti en inor xmembers can be increased by the -fitting of supporting brackets such as 100' to the webs 16,v as shown in Figure 10, and thatl the lengths of theliorizontal spans 25 between points of sup ort can also be increased by the fitting o sup orting brackets ves 47 at either or bot and webs.

30 to the transverses or we 15 and lon ituldinals or horizontals,as illustrated in igf' ure 6. f n

The projecting portions26 of the longitudinals or horizont-als can alsov be reinforced thefitting of a'stifl'ening, or reverse bar 7, and in such cases, the rejecting ends 26` of the longitudinals whic are unconnected by brackets to the transverse bulkheads 5 might be treated in making the calculations as free or supported as desired. The pro- 'ecting ortions can also be strengthened as fore' escribed b the fitting of brackets sides of the transverses The middle line bulkhead and transverse bulkhead can be manner. y

It is found that'the dimensions of a member such as`12 or 17 which was so disposed as to .make its middle portion 25 equal to or less than-its end portion 26, and which re` quires a bracket at its end, would not be suitable for another member 12 or 17 when the latters supports v16 and 1() are so spread,

as to make its middle portion 25 greater than its end'poitions 26, and which is not to be fitted with a bracket, as is the case in this invention.

len hs of the parts 25 and when not brackditions of service.

way of the transverse bulkheads Vas shown. Inthe case where fenders are fitted 'to the portion ofthe stiffener as compa l i ete 26 as well as their seantlin s will vary.

with the dimensions of the tan and con- When it is desired to maintain-the -full longitudinal 4strength of the structure, the

platinglcan be increased in thickness if desired in the wa of the unbrackete'd ends 26 'of 'the longitu inals, or plates of metal 35 called dou lings, see Figures 12, 3, 6, 7, 10 and 11, can e ftted'to the plating in the outsidefof the skin, the fender bars ycan be utilized to act for the saine purpose..4 When` f either of these constructions are adaptedthe ratio of' the length 26 of the rojecting red with the likewise dealt with in like In other words, the` bracketed ends- 26'; of. the longitudinaleor,fi T0." back bai-sl 50 and". 51,-Figures `10fy andlj1`1`,f .attached to the plating, andto the',lon'gitu-j Y dinal orhorizontal members,and theseiivillll horizontalsl can when desired' be fitted 'with have the effect ofreducing The construction shown' in Figure `2"isA the same as that shown in I`igur e 1,'w.ithvl the-length dus) doublings 35- when they are fitted. z 75 'l the addition ofthe reinforcing member 28,'

tion of Fi ure 6 is the saine as in Figue i1,- except the rackets30 areftted to thetrans-i Yat the ends of the longitudinal andA heide-ff f zontal stifleneis 7, and 12, as illustrated.l

The same-remarksapplyto Figure 3,' exfcept the reinforcin r members 36 and A37- ar'e somewhat different y placed. The construc4'-'.

"verses 16 and to the-webs`10 asillustrated. --f n The construction illustrated in Figure 7s the same as that `shown in Fi onllylho'ne transverse 32 is fitte' between t 'e bul eads 5 and onl one web'46 is'fitted' to4`v re 1,"exce t the' bulkheads 5 as s ownJ Brackets'-47'may or may not be fittedto tr'ansverses v"2 and webs 46, as desired., A I

The construction shownin Figure 1 0 is the same as that shown in Figures 1 and 2 ex'- ,95` cept the back bars 50 and 51 are differently placed, and attached \to both the longitudif 4 nals and-plating.

What is claimed is: v ,1. 'In a. liquid cargp carrying vessel provided with a tank having walls, the combina` tion of longitudinally and horizontally discposed. stifening members secured to said walls and of lengths in suflcient for their,A

ends to reach to-the corners of said tank;*' and vertically disposed stifenin 'members secured to saidwalls `and to said rst named i members, the ends offsaid stifl'ening members bein devoid of brackets. 1 2..v n; a vesselprovided with a tank adapt-V44 ed to carry a liquid cargo and havingverticallydisposed walls the combination of lioriv zontally-dis osed stifl'ening members rigid with said wa ls and of lengthsinsuicient tov reach the corners of said tank.; yand verticallly. s

dis sed stiiening webs secured to said'wal an to said first named stiffening members between the ends of the latter, said webs 4 i A being'so Vs read that' the lengths of said ends beyon said webs are less than the -distances between said webs.

" 3. In a tank for an oil carrying vessel,

the combination vof longitudinally and hori-Y zontally disposed stifl'ening members rigid with the wa lsuof Said tank; and al plurality of verticall disposed sti'ening members, on

'each wall, tween lwhich and beyond lwhich a pluralit of said sti en' members extends, sai verticallyd spo -members be` .l ing so spaced that the extending endsof 1o f v len hs in'suicient to reach to the corners of sai tank; and vertically disposed stiiening members secured to said wa ls and'to said first named members.

5. In a vessel provided with a tank adapt-- ed to carry a liquid cargo and having vertically disposed walls the combination of horizontally disposed stifenin members rigid with said walls whose en s are free from brackets, and of lengths insufficient to reach the corners of said tank;` and spaced verticall dis ed stitening webs secured to said wal s an to said first named stil'enng members between the ends of the latte-r, the

25 lengths of said ends beyond said Vwebs being less than the distance between said Webs.

6. In a tank for an oil carrying vessel, the

meses@ combination of longitudinally and horizonf tally disposed stiiening members rigid with the walls ofv said tank; and a lurality of vertically disposed stifenin we like members on each wall between W lich and beyond which a plurality of said stiiening members extends, the extendin ends of said members being unbracketed an shorter than the space between said vertically disposed members, and said ends being of a length insuiiicient to reach the corners of said tank'.

7. In a li uid cargo carrying Vessel provided with a tan deck, the combination of longitudinally disposed stiffening members secured to one of said walls, the ends of said members termineting short of the adjacent tank Walls and bein devoid of brackets; transversely dispoe stiifening members secured to one of said walls; and spaced stiening members crossing said first named members, forming spans between them which are longer than the unbracketed ends on each sideof said stiening members.

ln testimony whereof I ax my signature.

JSEPH W. ISHERWOOD.

having walls and carried on a Htl 

